1. Field of the Invention
The present invention generally relates to an etching method and an etching apparatus.
2. Description of the Related Art
There is proposed a method for etching a target etching layer containing polycrystalline silicon by using plasma generated by supplying HBr (hydrogen bromide) gas, NF3 (nitrogen trifluoride) gas, and O2 (oxygen) gas (See, for example, Japanese Laid-Open Patent Application No. 2013-258244).
However, in a case of forming a hole in a silicon film by etching, “twisting” occurs when the aspect ratio becomes, for example, greater than or equal to 15. “Twisting” is a phenomenon in which a tip of an etched hole becomes twisted and results into degradation of the shape of the etched hole. In recent years, the problem of twisting is increasing particularly due to the increase in the demand for smaller devices and high-aspect ratio etching.
One aspect of the present invention aims to improve the shape of an etched object.